Numerous chemicals have been proposed for controlling diseases of agricultural and horticultural crops. For example, Patent Document 1 discloses a tetrazoyl oxime derivative having superior pharmacological efficacy on useful plants and proposes the use thereof as a plant disease control agent. Examples of methods for producing the tetrazoyl oxime derivative disclosed in Patent Document 1 include the method described in Patent Document 2 whereby a hydroxylamine is reacted with a 1-alkyl-5-benzoyl-1H-tetrazole derivative represented by the following general formula (P) and the resulting tetrazoylhydroxyimino derivative is used as raw material to produce a tetrazoyl oxime derivative.

In general formula (P), A′ represents a halogen atom, alkyl group, alkoxy group, methanesulfonyl group, trifluoromethyl group, aryl group, cyano group or nitro group, n represents an integer of 0 to 5, and Y′ represents an optionally substituted alkyl group.
The method for producing the 1-alkyl-5-benzoyl-1H-tetrazole derivative represented by general formula (P) preferably consists of directly reacting benzoyl cyanide and an alkyl azide followed by forming a tetrazole ring by a cycloaddition reaction since it is easy to control the locations of substituents on the tetrazole ring.
For example, Non-Patent Document 1 reports that (1-benzyl-1H-tetrazol-5-yl)(phenyl)methanone was able to be synthesized by reacting benzoyl cyanide and benzyl azide for 60 hours in an autoclave. However, although the aforementioned method does not present problems in the case the alkyl azide used as raw material has a group having a comparatively long carbon chain such as a benzyl group, in the case of using a highly explosive raw material having a low boiling point in the manner of methyl azide, it becomes extremely difficult to carry out the method from the viewpoint of safety. Moreover, there is also the problem of the reaction requiring a long period of time to obtain an adequate reaction yield.
In addition, Patent Document 3 reports that 1-methyl-5-tosyl-1H-tetrazole was able to be synthesized by reacting methyl azide and tosyl cyanide in an explosion-proof, sealed autoclave. However, since highly reactive tosyl cyanide is used as a raw material in the aforementioned method, the target reaction product is obtained under comparatively low temperature conditions of 80° C., and reaction efficiency becomes extremely low in the case of using a benzoyl cyanide having a lower level of reactivity.
Moreover, Patent Document 4 reports that a compound represented by general formula (P′) (wherein, A′ and n are the same as in general formula (P)) was able to be synthesized efficiently and safely by reacting an alkyl isocyanide such as methyl isocyanide with an acid halide such as benzoyl chloride followed by reacting the aforementioned reaction product with sodium azide. However, the method described in the aforementioned document requires that the methyl isocyanide be isolated due to concerns over explosion and toxicity. Moreover, it is extremely difficult to industrialize the aforementioned method due to the extremely distressing odor of methyl isocyanide.

In addition, Non-Patent Document 2 reports that a tetrazole cyclization reaction was carried out by reacting benzyl cyanide and sodium azide in a flow reactor. However, a reaction using benzoyl cyanide and methyl azide as raw materials is not disclosed.